About 7 million years ago in the region of the Rift Valley in eastern Africa there is an ape. It is small, compared to us; maybe just a metre tall but it is hard to tell as it sits in the lower branches of a tree. It’s cautious, looking intently around the base of the tree; you get the distinct impression that it is thinking.
After what seems like an eternity, the ape does something remarkable: it jumps down to the ground and walks to the next tree some fifty metres away. It doesn’t knuckle walk, mind you, the way you’ve seen chimpanzees do it. It stands all but upright on its hind legs and ambles over to the tree. It isn’t an elegant walk, you get the impression it couldn’t keep it up for long, but it is a walk.
This ape is our last common ancestor with today’s chimpanzees. It is neither us, nor chimp; it is other. As you roam through the valley over the next couple of million years you see many apes – except some of them start to look more and more like us. They get taller as they spend more time on two legs on the ground rather than climbing in the trees. Another million years passes by and, by now, most of eastern and southern Africa has got such apes strolling across the grasslands.
After careful scrutiny you realise that this is not just one species of ape, but several. Some of them look more like us than others but they are definitely still not us. Nevertheless you follow these apes for another two million years as they begin to use stones as tools.
All of a sudden you notice something.
The apes, they’re not apes anymore. They’re… human; they’re people. They’re not the mirror image of you but, they are, undeniably people. These people start to become better hunters, it’s probably the flakes of stone they use in their weapons. Around about now you see them using fire as a tool as well and all of a sudden there is no stopping them. They begin extending their range as they become ever more skilled and confident. They begin to explore the land further afield as their numbers increase, they move up and out of Africa and into the Middle East.
The first few of these proto-people do pretty well; they colonise almost all of Europe and Asia. Eventually, though, they are replaced by a young upstart, also from Africa, that in just 150,000 years becomes a space faring species.
That, dear reader, is a rough outline of how we as a species came to be but, also, whence we came to be. The Out of Africa theory is now widely accepted and has a lot of independent lines of evidence to back it up. It isn’t impossible that it is wrong but it would be a bold claim to say that humans evolved anywhere else and, as Carl Sagan said: extraordinary claims require extraordinary evidence.
Extraordinary evidence is what is sorely lacking from a new open access paper in PLOSone. During the second world war a single mandible with most of the teeth still in situ was found near Athens. It has been dated to about 7.2 million years old, which is impressively ancient. At that age and in that location the specimen, named Graecopithecus freybergi, was classified as a type of ancient ape, a hominid.
The new analysis just published, however, claims that the morphology of the root of some of the teeth is more like that of a hominin, an ancient human. If this were true then it would be a staggeringly important finding and we would have to completely rework our theories about how and when modern humans evolved. It isn’t impossible, stranger things have happened, but the evidence feels thin.
In apes, the two roots of the second premolar are distinct, in people they are more fused. G. freybergi has a partially fused root of the second premolar. That’s it. That’s their whole portfolio of evidence. Personally, I don’t buy it. They may well be right, but this isn’t nearly enough evidence to prove it. I will not be rushing to update by mental map of how waves of early humans swept out through Africa all over the globe any time soon.
Ultimately, data will decide this. We need more specimens of G. freybergi, preferably a skull and some hips. Until then the question will remain unanswered and highly speculative.